A shady Las Vegas informant testified yesterday that the FBI sicced him on alleged mob cop Louis Eppolito after first saying the former cop was a waste of his snitching time.

Stephen Corso – an accountant who took to wearing a wire around Las Vegas after a 2003 conviction for misappropriating funds – said he asked his FBI handler if he should get involved in Eppolito’s filmmaking efforts.

The handler “told me to stay away from him, that you wanted nothing to do with him, that he was a cop,” Corso recounted. But the handler later changed his tune.

Corso ended up recording hours of talks with the ex-cop, who’s accused, along with ex-partner Stephen Caracappa, of aiding the Luchese crime family.

The talks eventually turned to Eppolito’s involvement in evading taxes, drug dealing and relationship with John Gotti.

Also, Det. Steven Rodriguez of the criminal-records division said Caracappa pulled records that might have led the mob to mistakenly kill a Brooklyn man in 1986.